Field of the Invention
The present invention relates to a gas filling method. More specifically, the present invention relates to a gas filling method including connecting a supply source of a compressed gas to a tank mounted on a mobile object, and filling the tank with the gas.
Related Art
A fuel cell vehicle runs on a motor powered by a fuel cell where air containing oxygen and hydrogen gas as a fuel gas supplied thereto generate electricity. Fuel cell vehicles, in which those fuel cells are used as energy sources for generating power, recently have been becoming closer to practical use. Hydrogen gas is required to generate electricity in a fuel cell. A recent mainstream fuel cell vehicle uses tank-filled hydrogen gas for running, in which a sufficient amount of hydrogen gas has been stored in a high-pressure tank or a hydrogen tank comprising an occluding alloy. Accordingly, filling technologies for quickly filling a tank with as much hydrogen gas as possible have also been actively explored.
Patent Document 1 discloses a table where a relationship is determined between a tank pressure (hereinafter, may simply be referred to as “initial pressure”) and temperature (hereinafter, may simply be referred to as “initial temperature”) just before starting main filling and a filling flow rate (or a rate of pressure increase) in main filling suitable for these. In the invention according to Patent Document 1, hydrogen gas is transferred to a tank of a vehicle from a hydrogen station at a filling flow rate determined using the aforementioned table for main filling. In order to achieve such a rapid filling, a technology are required for allowing a hydrogen station which controls a filling flow rate to accurately determine the initial pressure of a tank of a vehicle.
FIG. 7 schematically shows a procedure for the gas filling method called the pre-shot method. With reference to FIG. 7, a filling nozzle 102 provided at the front end of a station piping 101 extending from a compressed gas supply source 100 of a hydrogen station is connected to a receptacle 112 provided at the front end of a vehicle piping 111 extending from a tank 110 of a vehicle. This connection between the compressed gas supply source 100 and the tank 110 through a single piping enables hydrogen gas to be transferred to the tank 110 from the compressed gas supply source 100.
According to the pre-shot method, a flow control valve 103 provided in the station piping 101 is first fully closed, and a cutoff valve 104 provided upstream thereof is then opened with the flow control valve 103 closed, and the inside of the station piping 101 is pressurized until an output from a pressure sensor 105 provided upstream of the flow control valve 103 shows a predetermined value, and then the cutoff valve 104 is closed. This allows a section between the flow control valve 103 and the cutoff valve 104 in the station piping 101 to be filled with a certain amount of compressed hydrogen gas depending on the pressure. Subsequently, when the flow control valve 103 is opened with the cutoff valve 104 closed, high-pressure hydrogen gas stored inside the station piping 101 flows into the tank 110 at once to equalize the pressures in the tank 110 and the station piping 101. In this way, the pre-shot method can quickly determine the pressure in the tank 110 before starting main filling, i.e., the initial pressure in the tank, using the pressure sensor 105 provided at the station piping 101.    Patent Document 1: PCT International Publication No. WO2011/058782